Designation: A242/A242M − 13 American Association StateHighway and Transportation Officials

Standard AASHTO No.: M 161

Standard Specification forHigh-Strength Low-Alloy Structural Steel1

This standard is issued under the fixed designation A242/A242M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.

This standard has been approved for use by agencies of the Department of Defense.

1. Scope*

1.1 This specification covers high-strength low-alloy struc-tural steel shapes, plates, and bars for welded, riveted, or boltedconstruction intended primarily for use as structural memberswhere savings in weight [mass] or added durability areimportant. The atmospheric corrosion resistance of the steel inmost environments is substantially better than that of carbonstructural steels with or without copper addition. When prop-erly exposed to the atmosphere, this steel can be used bare(unpainted) for many applications (see Note 1). This specifi-cation is limited to material up to 4 in. [100 mm], inclusive, inthickness.

NOTE 1—For methods of estimating the atmospheric corrosion resis-tance of low-alloy steels, see Guide G101.

1.2 When the steel is to be welded, it is presupposed that awelding procedure suitable for the grade of steel and intendeduse or service will be utilized. See Appendix X3 of Specifica-tion A6/A6M for information on weldability.

1.3 The values stated in either inch-pound units or SI unitsare to be regarded as standard. Within the text, the SI units areshown in brackets. The values stated in each system are notexact equivalents; therefore, each system must be used inde-pendently of the other. Combining values from the two systemsmay result in nonconformance with the specification.

1.4 For structural products produced from coil and fur-nished without heat treatment or with stress relieving only, theadditional requirements, including additional testing require-ments and the reporting of additional test results, of Specifi-cation A6/A6M apply.

2. Referenced Documents

2.1 ASTM Standards:2

A6/A6M Specification for General Requirements for RolledStructural Steel Bars, Plates, Shapes, and Sheet Piling

G101 Guide for Estimating the Atmospheric Corrosion Re-sistance of Low-Alloy Steels

3. General Requirements for Delivery

3.1 Structural products furnished under this specificationshall conform to the requirements of the current edition ofSpecification A6/A6M, for the specific structural productordered, unless a conflict exists, in which case this specificationshall prevail.

3.2 Coils are excluded from qualification to this specifica-tion until they are processed into a finished structural product.Structural products produced from coil means structural prod-ucts that have been cut to individual lengths from a coil. Theprocessor directly controls, or is responsible for, the operationsinvolved in the processing of a coil into a finished structuralproduct. Such operations include decoiling, leveling orstraightening, hot-forming or cold-forming (if applicable),cutting to length, testing, inspection, conditioning, heat treat-ment (if applicable), packaging, marking, loading for shipment,and certification.

NOTE 2—For structural products produced from coil and furnishedwithout heat treatment or with stress relieving only, two test results are tobe reported for each qualifying coil. Additional requirements regardingstructural products produced from coil are described in SpecificationA6/A6M.

4. Materials and Manufacture

4.1 The steel shall be killed.

1 This specification is under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel and Related Alloys and is the direct responsibility of SubcommitteeA01.02 on Structural Steel for Bridges, Buildings, Rolling Stock and Ships.

Current edition approved May 1, 2013. Published June 2013. Originallyapproved in 1941. Last previous edition approved in 2009 as A242/A242M – 04(2009). DOI: 10.1520/A0242_A0242M-13.

2 For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at service@astm.org. For Annual Book of ASTMStandards volume information, refer to the standard’s Document Summary page onthe ASTM website.

*A Summary of Changes section appears at the end of this standard

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5. Chemical Composition

5.1 The heat analysis shall conform to the requirementsprescribed in Table 2.

5.2 The steel shall conform on product analysis to therequirements prescribed in Table 2, subject to the productanalysis tolerances in Specification A6/A6M.

5.3 Choice and use of alloying elements, combined withcarbon, manganese, phosphorus, sulfur, and copper within thelimits prescribed in 5.1 to give the mechanical propertiesprescribed in Section 6 and to provide the atmospheric corro-sion resistance of 1.1, shall be made by the manufacturer andincluded and reported in the heat analysis to identify the type

of steel applied. Elements commonly added include:chromium, nickel, silicon, vanadium, titanium, and zirconium.

5.4 The atmospheric corrosion-resistance index, calculatedon the basis of the heat analysis of the steel, as described inGuide G101–Predictive Method Based on the Data of Larabeeand Coburn, shall be 6.0 or higher.

NOTE 3—The user is cautioned that the Guide G101 predictive equation(Predictive Method Based on the Data of Larabee and Coburn) forcalculation of an atmospheric corrosion-resistance index has only beenverified for the composition limits stated in the guide.

5.5 When required, the manufacturer shall supply evidenceof corrosion resistance satisfactory to the purchaser.

6. Tension Test

6.1 The material as represented by the test specimens shallconform to the requirements as to tensile properties prescribedin Table 1.

7. Keywords

7.1 atmospheric corrosion resistance; bars; bolted construc-tion; durability; high-strength; low-alloy; plates; riveted con-struction; shapes; steel; structural steel; weight; welded con-struction

SUPPLEMENTARY REQUIREMENTS

Standardized supplementary requirements for use at the option of the purchaser are listed inSpecification A6/A6M. Those that are considered suitable for use with this specification are listed bytitle:

S2. Product Analysis,S3. Simulated Post-Weld Heat Treatment of Mechanical

Test Coupons,S5. Charpy V-Notch Impact Test,S6. Drop Weight Test (for Material 0.625 in. [16 mm] and

over in Thickness),

S8. Ultrasonic Examination, and

S15. Reduction of Area Measurement.

S32. Single Heat Bundles.

TABLE 1 Tensile Requirements

Plates and BarsA Structural Shapes

For thicknesses3⁄4 in.[20 mm],andunder

For thicknessesover3⁄4 to 11⁄2 in.[20 to 40mm], incl

For thicknessesover11⁄2 to 4 in.[40 to 100mm], incl

For flange orleg thicknesses1.5 in. [40 mm]and under

For flangethicknessesover 1.5 in.[40 mm] to2 in. [50mm], incl

For flangethicknessesover 2 in.[50 mm]

Tensile strength, min, ksi [MPa] 70 [480] 67 [460] 63 [435] 70 [485] 67 [460] 63 [435]Yield point, min, ksi [MPa] 50 [345] 46 [315] 42 [290] 50 [345] 46 [315] 42 [290]Elongation in 8 in. [200 mm], min, % 18B,C 18B,C 18B,C 18C 18 18Elongation in 2 in. [50 mm], min, % 21C 21C 21C 21 21 21D

A See the Orientation subsection in the Tension Tests section of Specification A6/A6M.B Elongation not required to be determined for floor plate.C For plates wider than 24 in. [600 mm] the elongation requirement is reduced two percentage points. See the Elongation Requirement Adjustments subsection in theTension Tests section of Specification A6/A6M.D For wide flange shapes over 426 lb/ft [634 kg/m], elongation in 2 in. [50 mm] of 18 % minimum applies.

TABLE 2 Chemical Requirements (Heat Analysis)

ElementComposition, %

Type 1

Carbon, max 0.15Manganese, max 1.00Phosphorus, max 0.15Sulfur, max 0.05Copper, min 0.20

A242/A242M − 13

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SUMMARY OF CHANGES

Committee A01 has identified the location of selected changes to this standard since the last issue(A242/A242M – 04 (2009)) that may impact the use of this standard. (Approved May 1, 2013.)

(1) Revised 4.1 to require killed steels.

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A242/A242M − 13

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